Fumigants are added to anhydrous ammonia used as an agricultural fertilizer in order to control the Nitrosomonas bacteria in the soil that would, if not inhibited by the fumigant, convert the nitrogen in ammonia to a nitrate that can be more easily leached away as compared with the less soluble forms of nitrogen. It is desirable to apply the ammonia to the soil in the fall of the year when the farmer has more time available for conditioning the soil. But if the conversion of ammonia to the nitrate is not inhibited, the winter precipitation, especially in the warmer climates where the bacterial conversion is faster, permits the valuable nitrogen nutrient to be converted to the nitrate form and leached from the soil. Fumigants applied with the ammonia in the fall season are active to inhibit this bacterial conversion of the ammonia and even though the anhydrous ammonia is spread in the fall, when a fumigant is present, the nitrogen in the ammonia is not subject to the undesired bacterial action and is thus preserved through the winter and into the growing season for assimulation by the spring crops.
One of the more popular fumigants is 2-chloro-6 (trichloromethyl) pyridine available from Dow Chemical Company under the name N-Serve. This chemical is available commercially in a petroleum solvent, normally xylene, that is rather volatile at high ambient temperatures and vaporizes easily if the pressure on the solution is reduced too greatly, as may sometimes happen during the course of the intake cycle of a conventional piston pump.
Since the introduction of N-Serve as an additive to be applied with anhydrous ammonia by mixing the ammonia and N-Serve together in a pressure tank to be applied as a solution to the soil, it has been observed that the resulting mix is corrosive when used in the equipment usually provided for containing and injecting ammonia. The aluminum valves and fittings are damaged by the flow of the resulting solution, including the corrosive fumigant, to the extent that the fittings become unreliable.